The present invention relates to a method for analysing a plurality of hydrocarbons contained in a drilling fluid, of the type comprising the following steps:                extraction of the gases contained in the fluid in an extractor in order to obtain continuously, at an outlet of the extractor, a gas stream of extracted gases containing hydrocarbons to be analysed and at least one interfering compound other than water and more polar than the hydrocarbons to be analysed;        transport of the gas stream through a transport line connected to the outlet of the extractor;        passing of the gas stream into a separation column connected to the transport line, in order to separate the hydrocarbons to be analysed according to their elution time in the separation column;        successive detection and/or quantification of each hydrocarbon to be analysed in a detector placed at the outlet of the separation column;        
the or each interfering compound being liable to have an elution time in the separation column of between the elution time in the separation column of the first hydrocarbon to be analysed and the elution time in the separation column of the last hydrocarbon to be analysed.
When drilling an oil well or a well for another effluent (in particular gas, vapour, water), it is known to carry out an analysis of the gaseous compounds contained in the drilling muds emerging from the well. This analysis makes it possible to reconstruct the geological sequence of the formations which are passed through during the drilling operation, and plays a part in determining the possibilities for exploiting the deposits of fluids encountered.
This analysis, which is carried out continuously, comprises two main phases. The first phase consists of extracting the gases carried by the mud (for example hydrocarbons, carbon dioxide, hydrogen sulphide, helium and nitrogen). The second phase consists of qualifying and quantifying the gases extracted. In the first phase, mechanically agitated degassers of the aforementioned type (FR-A-2 799 790) are frequently used. The gases extracted from the mud, which are mixed with a carrier gas introduced into the enclosure, are conveyed by suction via the gas extraction pipe to an analyser which permits the extracted gases to be quantified.